render: --shrink N - downscale the half-block live display (1-4)

Decimates the LCD N x N before the half-block encode so the monitor pane
takes 160/N cols x 72/N rows. Display-only: capture, recording and sixel
still read the full-res framebuffer.

Decimation is max-luma pick, not box-average: terminal fonts are 1px
bright strokes on dark background, and averaging dims them into grey
mush (the 'blurry font' regression). Keeping the brightest source pixel
of each block preserves stroke brightness and hue.

1 files changed, 5 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index 0dec4df..811e0a4 100644
--- a/src/main.c
+++ b/src/main.c
@@ -76,6 +76,8 @@ static void print_usage(FILE *out, const char *prog) {
 "  --sixel [scale]    sixel graphics output; scale = pixel zoom 1-6 (def 2)\n"
 "  --chrome           draw a Game Boy body around the LCD (sixel display)\n"
 "  --palette NAME     recolor the LCD: dmg|green (pea green), pocket|gray\n"
+"  --shrink N         shrink the half-block display N x (1-4); capture and\n"
+"                     recording stay full-res\n"
 "  --green            alias for --palette dmg\n"
 "  --frameskip N      draw 1 of every (N+1) frames\n"
 "\n"
@@ -172,6 +174,9 @@ int main(int argc, char **argv) {
         } else if (!strcmp(a, "--sixel")) {
             sixel = true;
             if (has_val) sixel_scale = atoi(argv[++i]);
+        } else if (!strcmp(a, "--shrink")) {
+            if (!has_val) { fprintf(stderr, "%s: --shrink needs a value\n", prog); return 1; }
+            render_set_shrink(atoi(argv[++i]));
         } else if (!strcmp(a, "--chrome")) {
             chrome = true;
         } else if (!strcmp(a, "--palette")) {